1. The Field of the Invention
The present invention relates generally to optical transceiver modules. More specifically, the present invention relates to using a connector to electrically connect a box optical sub-assembly to an optical transceiver module's printed circuit board.
2. The Relevant Technology
The basic optical components of conventional transceivers include two optical sub-assemblies (OSAs); a transmitter optical sub-assembly (TOSA) and a receiver optical sub-assembly (ROSA). The TOSA receives electrical signals from a host device via circuitry of the transceiver module and generates a corresponding optical signal that is then transmitted to a remote node in an optical network. Conversely, the ROSA receives an incoming optical signal and outputs an electrical signal that can be processed by the host device. Additionally, most transceivers include a rigid printed circuit board (PCB) containing, among other things, control circuitry for the TOSA and ROSA.
There are various TOSAs that can be used within the transceiver module. Some TOSAs electrically connect with a laser driver mounted on the PCB. This laser driver delivers a modulated current to the TOSA to generate the optical signals to be sent through the optical network. Other TOSAs can include a ceramic or thin metal box that contains the laser driver and the other optical components associated with a TOSA. These later TOSAs are typically referred to as box TOSAs.
The connections between the optical sub-assemblies and the PCB in the transceiver module have various electrical and mechanical requirements. One of the most common electrical connection components used in conventional optical transceiver modules is a flexible printed circuit board, or “flex circuit,” that connects the PCB to leads associated with the optical subassembly, such as a box TOSA. Flex circuits have several advantages, including good electrical performance and radio frequency response. Advantageously, the flex circuits also have the ability to take up tolerances in the modules and to withstand stresses that arise during manufacture and operation of the modules.
While flex circuits have been widely used in recent years in optical transceiver modules, flex circuits represent a significant portion of the costs and labor required to manufacture transceiver modules. As the price of transceiver modules drops, the costs associated with flex circuits continue to represent an increasing proportion of the overall costs of transceiver modules. Due to the nature of flex circuits, the costs of producing flex circuits are generally higher than the cost of a PCB that performs the same functions.
Additionally, flex circuits by design do not provide secure mechanical attachment between the OSA and the PCB. This can adversely affect the operation of the transceiver module since any shock vibration or side loads can cause movement of the OSA, resulting in changes in the orientation of the OSA's optical axis relative to the transceiver module housing and the flex circuit and movement of the PCB relative to the OSA, thus misaligning the OSA and potentially varying the optical output power of the OSA.
Further, the use of flex circuits with box TOSAs can be problematic because the pins used to connect the box TOSA to the PCB can exit the box generally perpendicular to the longitudinal axis of the transceiver module. This results in the flex circuit being twisted or turned to make the necessary electrical connection with the PCB, which may require additional space and reduce manufacturability.